Vista - VISTA file sharing - Unable to Enable?

Has anyone had any problems enabling VISTA file sharing? Here's what is happening:

1. Control Panel
2. Network and Sharing Center
3. Click dropdown arrow for "File Sharing"
4. Select radio button for "Turn on file sharing"
5. Click Apply (UAC is turned off)

AND

Nothing happens!! File sharing is still "Off".

I'm having the exact same problem with "Network Discovery".

Any ideas??

Go into the Windows Firewall properties and under the exceptions tab, ensure Network Discovery and File and Printer Sharing have a tick next to thier names.

You pointed me in the right direction!!

This afternoon, as a quick fix, I manually added the TCP ports for remote desktop. I didn't realize the default entries were missing.

To fix my current problem, I clicked on Advanced and found a "Restore Defaults" button. The file sharing option is now back!

Thanks again!!